The invention relates to a sanitary single-lever mixer valve which can be used to control the mix of fluids and the volume of fluid supplied, and which includes a locking device to define an intermediate position of the valve between its fully closed and fully open positions. Such valves can be opened to the intermediate position during normal operation. Full output can nevertheless be obtained after overcoming the tangible resistance provided by the locking device.
A sanitary single-lever mixer valve of the above type is disclosed in DE-A-3822217. The locking device in the valve comprises openings on a pair of abutting guide surfaces and a spring element located in one of the openings, which is also received in the other opening when the openings are aligned. The spring element is deformed resiliently when the openings are not aligned. The spring element is essentially Z-shaped and is located in a correspondingly Z-shaped groove. It projects with a rounded nose beyond the guide surface into the opening in a movable plate cam co-operating with the guide surface in which the Z-shaped groove is formed. Corresponding spaces between the spring element and the groove which accommodates it ensure that the spring element can be elastically deformed. However, there is a danger of the spring element becoming worn relatively quickly during use of the valve. The same applies to another embodiment of the spring element that is disclosed in the document, which is elastically clamped in an approximate V-shape into the corresponding opening, so that an outwardly curved region rests with elastic force against the adjacent guide surface of the movable plate cam.